Access logs using the Hyperledger Besu API
Subscribe to events, such as logs, using either RPC Pub/Sub over WebSockets or filters over HTTP.
Access logs using the following Hyperledger Besu API methods:
Use eth_newFilter to create the filter before using eth_getFilterChanges and eth_getFilterLogs).
Access logs for private contracts using the equivalent priv_* methods and specifying the privacy group ID. For example, priv_getLogs.
Note
The following examples use the sample contract included in events and logs.
Create a filter
Create a filter using eth_newFilter.
Example
If the example contract was deployed to 0x42699a7612a82f1d9c36148af9c77354759b210b, the following request for eth_newFilter creates a filter to log when valueIndexed is set to 5:
{
"jsonrpc":"2.0",
"method":"eth_newFilter",
"params":[
{
"fromBlock":"earliest",
"toBlock":"latest",
"address":"0x42699a7612a82f1d9c36148af9c77354759b210b",
"topics":[
["0xd3610b1c54575b7f4f0dc03d210b8ac55624ae007679b7a928a4f25a709331a8"],
["0x0000000000000000000000000000000000000000000000000000000000000005"]
]
}
],
"id":1
}
eth_newFilter returns a filter ID hash (for example, 0x1ddf0c00989044e9b41cc0ae40272df3).
Poll a filter for changes
To poll the filter for changes since the last poll, use eth_getFilterChanges with the filter ID hash returned by eth_newFilter.
Example
If the contract had been executed twice since the last poll, with valueIndexed set to 1 and 5, eth_getFilterChanges returns only the log where the topic for valueIndexed is 5:
{
"jsonrpc": "2.0",
"id": 1,
"result": [
{
"logIndex": "0x0",
"removed": false,
"blockNumber": "0x21c",
"blockHash": "0xc7e6c9d5b9f522b2c9d2991546be0a8737e587beb6628c056f3c327a44b45132",
"transactionHash": "0xfd1a40f9fbf89c97b4545ec9db774c85e51dd8a3545f969418a22f9cb79417c5",
"transactionIndex": "0x0",
"address": "0x42699a7612a82f1d9c36148af9c77354759b210b",
"data": "0x0000000000000000000000000000000000000000000000000000000000000005",
"topics": [
"0xd3610b1c54575b7f4f0dc03d210b8ac55624ae007679b7a928a4f25a709331a8",
"0x0000000000000000000000000000000000000000000000000000000000000005"
]
}
]
}
Get all logs for a filter
To get all logs for a filter, use eth_getFilterLogs.
Example
If the contract had been executed twice with valueIndexed set to 5 since the filter was created using eth_newFilter, eth_getFilterLogs returns:
{
"jsonrpc": "2.0",
"id": 1,
"result": [
{
"logIndex": "0x0",
"removed": false,
"blockNumber": "0x1a7",
"blockHash": "0x4edda22a242ddc7bc51e2b6b11e63cd67be1af7389470cdea9c869768ff75d42",
"transactionHash": "0x9535bf8830a72ca7d0020df0b547adc4d0ecc4321b7d5b5d6beb1eccee5c0afa",
"transactionIndex": "0x0",
"address": "0x42699a7612a82f1d9c36148af9c77354759b210b",
"data": "0x0000000000000000000000000000000000000000000000000000000000000005",
"topics": [
"0xd3610b1c54575b7f4f0dc03d210b8ac55624ae007679b7a928a4f25a709331a8",
"0x0000000000000000000000000000000000000000000000000000000000000005"
]
},
{
"logIndex": "0x0",
"removed": false,
"blockNumber": "0x21c",
"blockHash": "0xc7e6c9d5b9f522b2c9d2991546be0a8737e587beb6628c056f3c327a44b45132",
"transactionHash": "0xfd1a40f9fbf89c97b4545ec9db774c85e51dd8a3545f969418a22f9cb79417c5",
"transactionIndex": "0x0",
"address": "0x42699a7612a82f1d9c36148af9c77354759b210b",
"data": "0x0000000000000000000000000000000000000000000000000000000000000005",
"topics": [
"0xd3610b1c54575b7f4f0dc03d210b8ac55624ae007679b7a928a4f25a709331a8",
"0x0000000000000000000000000000000000000000000000000000000000000005"
]
}
]
}
Tip
You can use eth_getLogs with a filter options object to get all logs matching the filter options instead of using eth_newFilter followed by eth_getFilterLogs.
Uninstall a filter
When a filter is no longer required, use eth_uninstallFilter to remove the filter.
Filters for private contracts
Filters for private contracts are created, accessed, and uninstalled using:
The privacy group ID must be specified as parameter 0 for the priv methods.
Example
{
"jsonrpc": "2.0",
"method": "priv_newFilter",
"params": [
"4rFldHM792LeP/e2WPkTXZedjwKuTr/KwCFTt6mBbkI=",
{
"fromBlock": "earliest",
"toBlock": "latest",
"addresses": ["0x991cc548c154b2953cc48c02f782e1314097dfbb"],
"topics": ["0x85bea11d86cefb165374e0f727bacf21dc2f4ea816493981ecf72dcfb212a410"]
}
],
"id": 1
}
Get logs using a filter options object
To get all logs for a filter options object, use eth_getLogs or priv_getLogs for a private contract.
Example
The following request for eth_getLogs returns all the logs where the example contract has been deployed to 0x42699a7612a82f1d9c36148af9c77354759b210b and executed with valueIndexed set to 5.
{
"jsonrpc":"2.0",
"method":"eth_getLogs",
"params":[
{
"fromBlock":"earliest",
"toBlock":"latest",
"address":"0x42699a7612a82f1d9c36148af9c77354759b210b",
"topics":[
["0xd3610b1c54575b7f4f0dc03d210b8ac55624ae007679b7a928a4f25a709331a8"],
["0x0000000000000000000000000000000000000000000000000000000000000005"]
]
}
],
"id":1
}
The above example returns the same result as calling eth_newFilter followed by eth_getFilterLogs.